Multiplier? I didn't think those bulldozer chips were unlocked. Maybe you're just pushing higher than the basic stock frequency and running it closer to the max turbo frequency all the time. In that case, it shouldn't error out... I'm lost here.

Well, if you go over that limit and overstress the power circuitry too much you'll just fry the board, like I did to that cheap Biostar board with a Phenom 9500 ages ago. Maybe your board has some kind of feature to prevent that from happening though, could explain the instability... or maybe just not enough voltage for whatever frequency you're trying to run. I dunno, all my OC experience lies with AM2+ and AM3 and I'm just now getting the hang of x58... don't have any first hand knowledge of those bulldozer processors.